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| #include <bits/stdc++.h>using namespace std; #define ll long long const int maxn = 100; //点数
const int INF = 0x3f3f3f3f; struct Edge {
int from, to, cap, flow, cost; Edge(int u, int v, int c, int f, int cc)
: from(u), to(v), cap(c), flow(f), cost(cc) {}
}; vector<long long> res; struct MCMF {
int n, m;
vector<Edge> edges;
vector<int> G[maxn];
int inq[maxn]; //是否在队列中
int d[maxn]; //bellmanford
int p[maxn]; //上一条弧
int a[maxn]; //可改进量
void init(int n) {
this->n = n;
for (int i = 0; i <= n; ++i) G[i].clear();
edges.clear();
} void addEdge(int from, int to, int cap, int cost) {
edges.emplace_back(Edge(from, to, cap, 0, cost));
edges.emplace_back(Edge(to, from, 0, 0, -cost));
m = int(edges.size());
G[from].emplace_back(m - 2);
G[to].emplace_back(m - 1);
} bool spfa(int s, int t, int &flow, ll &cost) {
for (int i = 1; i <= n; ++i) d[i] = INF;
memset(inq, 0, sizeof(inq));
d[s] = 0;
inq[s] = 1;
p[s] = 0;
queue<int> q;
a[s] = INF;
q.push(s);
while (!q.empty()) {
int u = q.front();
q.pop();
inq[u] = 0;
for (int i = 0; i < int(G[u].size()); ++i) {
Edge &e = edges[G[u][i]];
if (e.cap > e.flow && d[e.to] > d[u] + e.cost) {
d[e.to] = d[u] + e.cost;
p[e.to] = G[u][i];
a[e.to] = min(a[u], e.cap - e.flow);
if (!inq[e.to]) {
q.push(e.to);
inq[e.to] = 1;
}
}
}
}
if (d[t] == INF) return false;
flow += a[t];
cost += (ll) d[t] * (ll) a[t];
res.push_back(d[t]);
for (int u = t; u != s; u = edges[p[u]].from) {
edges[p[u]].flow += a[t];
edges[p[u] ^ 1].flow -= a[t];
}
return true;
} int MincostMaxflow(int s, int t, ll &cost) {
int flow = 0;
cost = 0;
while (spfa(s, t, flow, cost));
return flow;
}
} mcmf; int n, m; void solve() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.precision(10);
cout << fixed;
while (cin >> n >> m) {
mcmf.init(n + 10);
res.clear();
for (int i = 0; i < m; ++i) {
int u, v, f;
cin >> u >> v >> f;
mcmf.addEdge(u, v, 1, f);
}
ll cost = 0;
ll mf = mcmf.MincostMaxflow(1, n, cost);
int q;
cin >> q;
while (q--) {
ll u, v;
cin >> u >> v;
if (mf * u < v) {
cout << "NaN" << '\n';
continue;
}
ll sum = 0;
ll ans = 0;
for (auto item : res) {
if (sum + u <= v) {
sum += u;
ans += item * u;
} else {
ans += (v - sum) * item;
break;
}
}
ll g = __gcd(ans, v);
cout << ans / g << '/' << v / g << '\n';
}
}
} signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
#ifdef ACM_LOCAL
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
int test_index_for_debug = 1;
char acm_local_for_debug;
while (cin >> acm_local_for_debug) {
if (acm_local_for_debug == '$') exit(0);
cin.putback(acm_local_for_debug);
if (test_index_for_debug > 20) {
throw runtime_error("Check the stdin!!!");
}
auto start_clock_for_debug = clock();
solve();
auto end_clock_for_debug = clock();
cout << "Test " << test_index_for_debug << " successful" << endl;
cerr << "Test " << test_index_for_debug++ << " Run Time: "
<< double(end_clock_for_debug - start_clock_for_debug) / CLOCKS_PER_SEC << "s" << endl;
cout << "--------------------------------------------------" << endl;
}
#else
solve();
#endif
return 0;
}
|
